Airplane propeller



Feb. 7, 1928.

E. E. COTHRAN AIRPLANE PROPELLER Filed May 11. 1925 Patented Feb. 7, 1928.

EDWARD EVERETT COTHRAN, OF WRIGHT, CALIFORNIA.

AIRPLANE PROIPELLEB.

Application filed May 11,

The invention relates to a propeller for lifting, sustaining, moving and landin an airplane or other vehicle in the air, an the objects of the invention are, first, to enable airplanes to ascend vertically from the earth,

the water or a ship; second, to enable airplanes to descend vertically from the air; third, to enable airplanes to land safely from flight in the air upon earth, water or deck of a ship; fourth, to increase the carriying and sustaining capacity of airplanes; fth, to better the stability and safety of airplanes; and, sixth, to increase the power, speed and efficiency of airplanes in connection and combination with a tractor type of propeller.

I attain these objects by the mechanism illustrated in the accompanying drawing, in which Figure 1 is a diagrammatic view of part of the invention shown with the understructure of the airplane;

Figs. 2, 3 and 4 are detail views of the propeller blades; and Fig. 5 'a side view of a monoplane in accordance with my invention.

- Referring to Fig. 1, the understructure (1) of the airplane is pierced by the vertical shaft (2) and above such understructure is the crankshaft (3) of an engine, the an latter not shown.

Aflixed rigidly to the shaft (2) half of the propeller blades, fully disclosed in Figs. 2, 3, and 4, are shown.

The crankshaft (3) and the propeller shaft (2) are of one piece of metal.

While the vertical shaft indicates that a horizontal engine is employed preferably to a vertical engine, still, the latter may by appropriate gearing be used.

The blades shown in Fig. 1, are affixed to the propeller shaft (2) as illustrated in Figs. 2, 3,. and 4 with a squared cross-section of the shaft As the blades are all rigidly attached to .45 the shaft' (2) either by welding, bolts and lock-nuts or by some other suitable means, the vertical shaft is better made square after ,leaving its lowest bearing or journal-box in the understructure. 'v The four blades shown in Fig. 2 must be affixed, to the shaft (2) immediately below the understructurejl) Fig. 1, leaving only lear'ance s ace., These blades are of maxinm le'n'gt from tip to tip. -Th'gf6iir blades shown in Fig. 3 must be parts of the blades which should be made as 1925. Serial No. 29,493.

affixed to the said shaft next below the four blades of Fig. 2, leaving a small clearance, and are shorter from tip to tip.

The four blades shown in Fig. 4 must be affixed to the propellershaft next below the four blades of Fig. 3, leaving a small clearanceand are shortest from tip to tip.

In each of the three sets of blades, two blades are set at right angles to two blades, making a total of twelve propeller blades. All the blades are designed to move toward the right with the shaft to which'they are rigidly attached.

The direction may, of course, and shaft.

The propeller blades should be constructed of metal or wood, preferably of thin steel yvhitch combines tensile strength and elas- Referring in this connection to Figs. 2, 3, and 4, the edges of the respective blades, particularly at the spines (5, 5, 5, 5,) should be thicker and stronger than the remaining of the motion of the blades be reversed with the engine 10 thin, light and elastic as is consistent with the necessary strength.

Elasticity in the blades is important as it permits many small flexures that aid in the effective compression of the open air by the blades with the consequent increase of power.

The shoulders of the blades of Fig. 2 are very closely affixed to the propeller shaft.

' The shoulders of the blades of Figs. 3 and 4 are joined to the shaft by stout bolts (4) and lock-nuts or are joined by welding steel rods to the shaft and said shoulders, leavin in either case an opening of a few inches 0 space between the shaft and said shoulders for the purpose of allowing an unobstructed 5110- 05 tion of air upward pa t these two sets of blades.

The purpose of these arrangements is to allow the free ingress of air around the shaft and to cause the blades of Fig. 2 to strike a large volume of compressed air around the shaft.

As the vertical shaft and the three sets of blades of different lengths and curved surfaces are whirled around, the air is forced in 1 5 circles and spirals along the blades under a high compression, tending to produce a vacuum, (see Fig. 1) within the propeller.

However, this tendency to produce a vacuum is not realized, as a powerful suction from the air below is created within the area of the propeller, especially next the shaft.

This suction is naturally along the line of least resistance upward, thereby inducing great lifting force as the air rushes in to be impacted, compres-ed and thrust by all the blades.

The general outline of the entire propeller somewhat resembles the shape of a tornado, water-spout or whirlwind, and the mechanism operates qualifiedly upon similar prin ciples, namely; meeting of winds blowing in opposite directions, compression of air, production of partial temporary vacuums, and vortices of upward and translatory motion.

As a heavy object may be lifted more easily upon an inclined plane and as one of the primary purposes is to cause an alrplane to rise directly upward, the blades are not only multiplied beyond the ordinary number'employed in aerial propellers, but the lnclined planes, circular or screw-like in form, are very pronounced, particularly in F 1g. 3.

The blades in Fig. 2, largely compress and thrust the air downward and outward from the shaft (2), as a center to the tips as a circumference, forming a vortex of gyratlng air within and around the propeller.

The blades in Fig. 3, compress and thrust the air more outward and less downward in a circle than the blades in Fig. 2.

The blades in Fig. 4, being of min mum length from tip to tlp, and freely admitting air around the shaft, compress and thrust the air more largely outward in a circle.

The combined effects of the two sets of blades, shown in Figs. 3 and 4, are, first, to

increase the tendency of the propeller to form a vacuum next the vertical shaft, and, second, to oppose and prevent the vacuum beingv formed by simultaneously creating a powerful upward suction of air against the lower surfaces of the blades of Fig.2, especially around the shaft.

This suction, in turn, concentrates air under high compression, beneath the blades of Fig. 2.

The final result is a propeller of great lifting and sustaining power.

The application of the engines power through the propeller below the nnderstructure of the airplane lowers the center of gravity of the whole machine and contributes much to its stability.

The blades shown in Fig. 4, while shaped like those of Fig. 2, are reversed in the order in which they are afiixed to the shaft and in which they strike the air.

In other words, the four blades of Fig. 4, may be deemed upside down to the four blades of Fig. 2. i

As the shaft whirls -'all the blades in the same direction, this arrangement causes the air to be displaced and thrust in a different aesaeee manner and angles by these two sets of blades; and as the blades of Fig. 3, are unlike in shape to those of Figs. 2 and 4, all the three sets have different functions in the propeller.

he vertical propeller may be made to move the airplane horizontally by manipulation of the rudder, although it is the particular intention of petitioner to employ two engines in the airplane: one to drive the described propeller from a vertical shaft, another to drive a tractor propeller from a horizontal shaft.

Referring to Fig. 5, (6) shows a tractor propeller of four blades shaped precisely like the blades of F ig. 2, (7 is a monoplane body, (8) is a monoplane wing, (9) shows the vertical rudder, (10) the horizontal rudder, (11) the landing-gear, and, (2) the vertical propeller shaft with the blades atfixed to it.

The vertical propeller shaft and its described blades do not extend so far below the understructure of the airplane as to require any particular modification of the present landing-gear except that more space is allotted between the front and rearward gears.

A small clearance between the upper blades (Fig. 2) and the understructure (1) Fig. 1, allows of an exceedingly compact construction of the entire propeller.

The clearance spaces or rather distances between the blades of Fig. 2 and Fig. 3, and between the latter and Fig. 4 may, for instance, be not more than one inch.

Having described and illustrated'my invention, I claim:

1. An airplane propeller consisting of a vertical metal shaft, directly connected with the vertical crank-shaft of the airplane 611- engine, extending vertically downward through and beneath the understructure of the airplane, four compound-curved ropeller blades preferably of steel rigidly affixed at the shoulders of the blades to the shaft at right angles to each other and immediately beneath said understructure with only clearance space for the blades when whirled with the shaft, four shorter propeller blades of similar material, each blade more'acutel curved, rigidly affixed to the shaft at right angles to each other immediatelv beneath and without contact with the first-mentioned four blades, four compoundcurved and still shorter blades of similar material of the same shape as those firstmentioned but set upside down rigidly afiixed to the shaft by bolts and lock-nuts with the shoulders of the blades slightly separated from the shaft immediately be-' neath the second-named four blades and without contact with the latter.

2. An airplane propeller of thecharacter described and shown in combination with,

a monoplane andmonoplane propelleryconsisting' of a vertical metal shaft extending vertically downward through and beneath the nnderstructure of the monoplane, said shaft directly connected as one piece of metal with the crank-shaft of the mono planes engine, four compound-curved propeller blades, preferably of steel, rigldly afiixed at the shoulders of the blades to the vertical shaft at right angles to each other -and immediately beneath said understructure with only clearance space for the blades When whirled around with the Said shaft, four shorter propeller blades of similar ma- 5 ter'ial, each blade more acutely curved, rigidly afiixed to the shaft at rightlangles to each other, immediately beneath and without contact with the first-mentioned four blades; four compound-curved and still shorter propeller blades of similar material and of the. same shape as those first-mentioned but affixed to the shaft upside down by bolts and lock-nuts with the shoulders of the blades slightly separated from the shaft and the mono 1ane.-.

ED ARD EVERETT COTHRAN. 

